In recent years, the dental operatory has been identified as a possible location where contagious diseases can be transferred between individuals. This information has led to a variety of new products to minimize any possibility that diseases be transferred to an individual while that individual is receiving dental treatment. One procedure of concern in possibly transmitting contagious diseases is dental prophylaxis. During prophylaxis, a dental practitioner removes plaque, tartar, stains and other debris accumulating on the individual's teeth. This prophylaxis procedure is performed with a rotating prophylaxis cup which often includes an abrasive paste supported therein until it is applied to the teeth of the individual. The rotating prophylaxis cup is supported by a housing which also includes a fluid driven motor to cause the prophylaxis cup to rotate.
Handpieces are known in the art which are specifically provided to rotatably support the prophylaxis cup for performing dental prophylaxis. These handpieces include a housing which is sized to be easily grasped by a user and includes a fluid driven motor therein which has an output shaft coupled to the prophylaxis cup. The motor is coupled to a source of elevated pressure air which causes a rotor of the motor to rotate.
Dental prophylaxis handpieces have been identified as one possible site where contamination between individuals can occur, resulting in the transmission of communicable disease. To thwart such contamination, it is generally advised that practitioners thoroughly sterilize the handpieces between use. Such sterilization procedures are time-consuming and often result in damage to the handpiece, diminishing the handpiece's useful life. Hence, some practitioners resort to other, less effective, methods of sterilization or must purchase additional handpieces, increasing the cost to deliver this preventative dental maintenance procedure.
The known dental prophylaxis handpieces include fluid driven motors with dynamic rotors which rely on high pressure compressible fluids to operate. The rotor includes flat vanes which slide away from and toward a geometric center of the rotor. The rotor is located asymmetrically within a cylinder such that air passing from an inlet to an outlet within the cylinder causes the rotor to rotate in only one direction. The vanes slide away from and toward a rotational axis of the rotor as the rotor rotates. Because such sliding flat vane rotors contact a wall of the cylinder, friction exists which determines a maximum free speed of the rotor for a given air pressure. Such motors also exhibit relatively high torque at lower speeds than high velocity air motors.
While such sliding flat vane rotors are generally effective, the prophylaxis procedure requires higher torque at still lower speeds than those obtainable with flat sliding vane rotors. The current solution of gearing the output shaft to obtain desired speeds is too complex to facilitate economical disposability. Additionally, at start up flat sliding vane rotors require some form of system to extend the vanes away from the rotor before centrifugal forces are sufficient to maintain the vanes against a surrounding cylindrical wall. Finally, such flat sliding vane rotors must be formed with multiple pieces and to precise tolerances to ensure that the vanes can effectively slide within slots in the rotor. Such complexity makes single use of the handpiece economically prohibitive.
Accordingly, a need exists for a dental prophylaxis handpiece which has high torque at low speeds but which is easily manufactured and has vanes which extend readily when the motor is started. Such a handpiece would facilitate effective prophylaxis and yet could be economically discarded after a single use.
The following prior art reflects the state of the art of which applicant is aware and is included herewith to discharge applicant's acknowledged duty to disclose relevant prior art. However, it is respectfully submitted that none of these prior art devices teach singly, nor render obvious when considered in any conceivable combination, the nexus of the instant invention as especially claimed hereinafter.
______________________________________ INVENTOR PATENT NO, ISSUE DATE ______________________________________ Schmitz 263,814 September 5, 1882 Swisher et al 1,999,488 April 30, 1935 Wiseman 2,017,881 October 22, 1935 Roelke 2,025,779 December 31, 1935 Monnier, et al. 2,128,157 August 23, 1938 Blair 2,135,933 November 8, 1938 Smith 2,226,145 December 24, 1940 Goldenberg 2,300,828 November 3, 1942 Shotton 2,315,016 March 30, 1943 Greenberg 2,328,270 August 31, 1943 Wiseman 2,789,352 April 23, 1957 McFadden Re. 24,391 November 12, 1957 Kern 2,937,444 May 24, 1960 Wiseman 3,163,934 January 5, 1965 Winkler 3,192,922 July 6, 1965 Hoffmeister, et al. 3,229,369 January 18, 1966 Brehm, et al. 3,421,224 January 14, 1969 Smith 3,510,229 May 5, 1970 Graham 3,727,313 April 17, 1973 Brahler 3,740,853 June 26, 1973 Booth 3,855,704 December 24, 1974 Campagnuolo, et al. 3,856,432 December 24, 1974 Killick 3,877,574 April 15, 1975 Balson 3,955,284 May 11, 1976 Danne, et al. 3,987,550 October 26, 1976 Flatland 4,053,983 October 18, 1977 Gritter 4,1,71,571 October 23, 1979 Girard 4,182,041 January 8, 1980 Lewis 4,248,589 February 3, 1981 Warden et al. 4,259,071 March 31, 1981 Melcher 4,261,536 April 14, 1981 Warden et al. 4,266,933 May 12, 1981 Bailey 4,365,956 December 28, 1982 Karden 4,465,443 August 14, 1984 Geller 4,693,871 September 15, 1987 Buse 4,767,277 August 30, 1988 Choisser 4,795,343 January 3, 1989 Choisser 4,842,516 June 27, 1989 Stefanini 4,863,344 September 5, 1989 Moreschini 4,929,180 May 29, 1990 Kimura 4,941,828 July 17, 1990 Huang 5,020,994 June 4, 1991 Witherby 5,028,233 July 2, 1991 Falcon et al. 5,040,978 August 20, 1991 Rosenberg 5,062,796 November 5, 1991 Bailey 5,094,615 March 10, 1992 Butler 5,120,220 June 9, 1992 Bailey 5,156,547 October 20, 1992 ______________________________________ FOREIGN PATENT DOCUMENTS DOCUMENT SUB- FILING NUMBER DATE NAME CLASS CLASS* DATE ______________________________________ 646,193 06/1937 Durhager 30b 202 5/1937 (Germany) 102,433 05/1951 Callaghan 433 132 (New Zealand) GB 2 209 284-A 05/1989 Kalsha A61C 1/05 07/1988 Fed. Republic of June, 1937 Germany 646,193 ______________________________________